This invention relates generally to cutting, beveling and welding torches for carbon steel workpieces and more particularly concerns carriages for transporting and guiding such torches along a desired path on a workpiece.
Known torch carriages permit variation of the direction and speed of travel of only the carriage along the workpiece. Thus, the torch can only follow the carriage path and any variation in the work path from the carriage path can be accounted for only by reorienting the carriage on the workpiece. It is not presently possible to trace any desired path on a workpiece in a single remotely controlled operation of the carriage.
It is, therefore, an object of this invention to provide a torch carriage which enables an operator to accurately trace the torch along any narrow path on a workpiece. It is also an object of this invention to provide a torch carriage which enables an operator to remotely guide the travel of the torch along the desired workpiece path. An additional object of this invention is to provide a torch carriage which enables an operator to control the direction of travel of the torch in two dimensions. Still another objection of this invention is to provide a torch carriage which enables an operator to control the speed of travel of the torch in a direction transverse to the direction of the carriage. Another object of this invention is to provide a torch carriage capable of performing on vertically or horizontally oriented flat or arcuate workpieces. A further object of this invention is to provide a torch carriage which is capable of accurately tracing a narrow linear or nonlinear path on the outside or inside wall of a tubular workpiece. Yet another object of this invention is to provide a torch carriage which is firmly magnetically engaged with the workpiece regardless of its shape or orientation. Still another object of this invention is to provide a torch carriage which is easily disengaged from magnetic engagement with the workpiece. A further object of this invention is to provide a torch carriage which enables an operator to adjust the elevation or distance of the torch from the workpiece surface. Yet another object of this invention is to provide a torch carriage which enables an operator to adjust the angle of the torch with respect to the workpiece suitable so as to create a xe2x80x9cbevelxe2x80x9d on the workpiece. And it is an object of this invention to provide a torch carrier which permits selection of the transverse carriage and torch speeds so as to provide a miter angle on a workpiece.
In accordance with the invention, a carriage is provided for guiding a cutting, beveling or welding torch on the surface of a metal workpiece. The carriage has a chassis which is transported along a main path on the workpiece by a wheel assembly. The wheels of the assembly magnetically maintain engagement with the workpiece. A reversible motor mounted on the chassis drives the wheels so as to transport the chassis forward or backward along the main path. A rack and pinion assembly mounted on the chassis transports a torch holder along a path perpendicular to the main path. Another reversible motor mounted on the chassis drives the pinion of the rack and pinion assembly so as to transport the holder to the left or to the right along the perpendicular path. A remote controller electrically connected to the drive motors is manually operable to simultaneously permit forward or backward transport of the chassis and right or left transport of the holder, respectively, so as to accurately trace any cutting path on the workpiece with the torch. The remote controller has one toggle switch for selecting from the forward, off and backward operating conditions of the wheel assembly motor and another toggle switch for selecting from the left, off and right operating conditions of the rack and pinion motor. The controller is further manually operable to vary the angular velocity of the chassis motor and the rack and pinion motor, for example, by use of rheostats electrically connected to the motors. One mechanism, such as another rack and pinion assembly, is provided for manually adjusting the elevation of the torch above the workpiece and another mechanism is provided for manually adjusting the angle of incidence between the torch and the workpiece. A lift assembly permits manual disengagement of the magnetic wheel assembly from the workpiece. In a preferred lift assembly, an axle is journalled on the chassis for rotation about a longitudinal axis perpendicular to the main path of the chassis and a lever extends radially from the axle for a distance sufficient to permit engagement of the lever with the workpiece. A knob or crank on the lever facilitates manual rotation of the axle to engage the lever against the workpiece and pry the wheels from the workpiece. In order to limit deflection of the torch transport rack in relation to the chassis, at least two cams are spaced apart and rotatable to take up slack between the chassis and the torch transport rack. Set screws lock the cams in their selected angular position. A shield mounted on the chassis in the space between the wheel assembly and the torch holder protects the carriage components from the heat of the torch.